Although amiodarone has been reported to improve survival in at- risk patients with hypertrophic cardiomyopathy (HCM), we have noted an unexpected mortality rate in highly symptomatic HCM patients treated with this potent antiarrhythmic medication. The study reports the results of programed electrical stimulation (PS) in 14 HCM patients - 10 patients presented with syncope and 4 with presyncope. All patients had nonsustained ventricular tachycardia (VT) on Holter monitoring. Before amiodarone therapy, sustained VT was induced in 11 patients. In 10 patients the VT was polymorphic. On amiodarone, sustained VT was induced with significantly less aggressive PS protocol in all 14 patients. In 12 patients this was monomorphic VT. Although the VT was slower on amiodarone, in all patients induction of VT was associated with marked hypertension requiring rapid termination. We conclude that in most HCM patients amiodarone facilitates induction of a hemodynamically unstable sustained monomorphic VT and thus its use is potentially dangerous and requires evaluation by PS.